ESA GNC Conference Papers Repository

In the frame of AEROFAST project, granted in the Seventh European Community Framework Program (FP7) and coordinated by Astrium ST SAS, a complete GNC design, implementation and testing is performed for a mission whose aim is to perform an Aerocapture on Mars. Aerocapture is a new technology using a single pass through a planetary atmosphere to decelerate the spacecraft. Pre-aerocapture, which is the mission scenario phase from where relative navigation can start till the Entry Interface Point (EIP) with atmosphere, is very critical: it is demonstrated that a GNC function foreseeing both ground based radiometric and optical measurements in this phase is a key capability in achieving the required dispersion performance at the EIP (1 km 1?) and thus performing a successful aerocapture manoeuvre. This paper presents the GNC design and performance assessment for the pre-aerocapture phase. The GNC function foresees an orbital Navigation function based on a Square Root Information Filter, managing time tagged ground based radiometric measurements and time tagged optical measurements provided by a high precision camera and acquired in target pointing; orbital linear guidance to compute Trajectory Correction Manoeuvres; an ADCS state machine and attitude guidance profile generation. Attitude determination and control are modelled through performance models. The GNC function is tested in a high fidelity FES (Functional Engineering Simulator), which models complete Translational Dynamics and kinematics, rotational dynamics and kinematics through performance model, orbital perturbations, image acquisition by two cameras (not operating at the same time) and Image Processing performances. Validation and Verification activities are performed, demonstrating the feasibility of such a GNC function design.